As is known in the art, UV detectors are used in many applications including dual band IR and UV detectors. One method used to produce the Cadmium Sulfide (CdS), in hexagonal form, for such UV detectors, for example, has been to grow bulk CdS material starting with a CdS seed crystal using a vapor phase process as described in a paper entitled “SEEDED GROWTH OF LARGE SINGLE CRYSTALS OF CdS FROM VAPOR PHASE” by G. H. Dierssen and T. Gabor, 1978 published in Journal of Crystal Growth 43 (1978) 572-576. Wafers are sliced from this bulk crystal material, annealed, polished and etched to prepare them for use as Schottky diode UV detector. More particularly, the CdS layer is then cut or sliced into the appropriate thickness by slicing and dicing and then re-annealed in hot sulfur atmosphere to achieve detector electrical properties. In the case of a dual band UV and IR detector, then CdS is then glued to the surface of an infrared filter configured to pass the infrared portion of incident radiation. In the dual band detector, the IR filter is disposed between an upper UV detector and a lower IR detector, as shown in FIG. 1.
As is also known in the art, one method used to produce the hexagonal Cadmium Sulfide (CdS) material for IR polarizers, for example, has been to use germanium as a substrate and epitaxially grow a relatively thick layer of CdS on the <111> surface of the germanium substrate, as described a paper entitled “Epitaxial Growth of cadmium Sulfide on (111) on germanium (Ge) substrates”: by Paroici et al, in Journal of Material Science, 10 (1975) pages 2117-2123. The formed CdS material grows outwardly perpendicular to the <111> crystallographic plane of the Ge substrate; that is, the c-axis of the grown CdS is perpendicular the <111> surfaces of both the Ge and the grown CdS. The formed CdS is then used as infrared polarizer by positioning the hexagonal crystal c-axis of the formed CdS perpendicular to the Infrared (IR) light to be polarized; see Epitaxial growth of cadmium sulphide on (111) germanium substrates; C. PAORICI, C. PELOSI, G. BOLZON I, G. ZUCCALLI Laboratorio MASPEC-CNR, 43100 Parma, Italy; JOURNAL OF MATERIALS SCIENCE 10 (1975) 2117-2123.